The present invention is generally directed to ink jet printers. More particularly, the invention is directed to identification of print heads installed in ink jet printers.
Increasingly, ink jet printers in all price ranges provide multicolor printing capabilities. Typically, these printers include one print head for printing in black ink, and at least one other print head for printing in multiple colors of ink, such as magenta, cyan, and yellow. These print heads are usually replaceable and disposable, so that a new print head may be installed when the ink supply in the print head is depleted.
In many print head designs, the black and multicolor print heads are physically interchangeable, such that any type of print head may be installed in any available installation slot in the printer carriage. Since the format of print data provided to a black print head is generally different from the format of print data provided to a multicolor print head, the printer should be able to identify which type of print head is installed in each installation slot so that print data may be routed appropriately.
Prior techniques have been devised for storing print head identification information on a print head and for accessing that information to identify the type of print head installed in a particular carriage location. However, these prior techniques have required additional memory modules on the print head, and/or a significant number of additional input/output lines between the print head and the printer controller to implement the identification scheme. Such additional memory modules and input/output lines add significant additional complexity to the disposable print heads, thereby increasing their cost.
Therefore, a print head identification system is needed, the implementation of which requires a minimal number of input/output lines and no additional memory modules on the print head.
The foregoing and other needs are met by an apparatus for providing identification information related to at least one ink jet print head in an ink jet printer. In preferred embodiments, the apparatus includes a printer controller for providing a first identification data string comprising n number of bits, where at least one of the bits in the first identification data string has a first state, and no more than nxe2x88x921 number of the bits in the first string have a second state different from the first state. Coupled to the printer controller is a first ink jet print head which includes a first serial input shift register. The first serial input shift register has at least n number of bit positions for receiving the n number of bits of the first identification data string from the printer controller. The first ink jet print head also includes at least n number of first latches, each of which is coupled to a corresponding one of the n number of bit positions of the first shift register. The n number of first latches are for latching the n number of bits of the first identification data string from the n number of bit positions of the first shift register. A first identification line is coupled to a predetermined one of the first latches and to the printer controller. The first identification line provides to the printer controller one of the n number of bits from the first identification data string that is latched into the predetermined one of the first latches. Based upon whether the bit provided on the first identification line has a first or second state, the printer controller determines whether the first print head is of a first type.
Preferably, the first serial input shift register is the same input shift register used to receive print data during normal printing operations. Thus, the present invention provides for identifying the type of print head installed without adding a significant amount of additional circuitry to the print head.
In another aspect, the invention provides an apparatus for providing identification information related to at least one ink jet print head having ink ejecting elements. The apparatus includes a printer controller that is operable in a normal print mode and in a print head identification mode. When in the print head identification mode, the printer controller provides at least one identification data string having n number of bits, where at least one of the bits in the identification data string has a first state, and no more than nxe2x88x921 number of the bits in the identification data string have a second state different from the first state. When in the normal print mode, the printer controller provides a print data string having at least nxe2x88x921 number of bits related to an image to be printed. Coupled to the printer controller is an ink jet print head. The ink jet print head preferably includes a serial input shift register having at least n number of bit positions for receiving the n number of bits of the identification data string or the nxe2x88x921 number of bits of the print data string from the printer controller. The print head also has at least n number of latches, each of which is coupled to a corresponding one of the n number of bit positions of the shift register. The latches are for latching the n number of bits of the identification data string or the nxe2x88x921 number of bits of the print data string from the n number of bit positions of the shift register. Selection logic circuitry in the print head receives the nxe2x88x921 number of bits of the print data string from the n number of latches, and selects particular ink ejecting elements in the print head to be activated based at least in part on the nxe2x88x921 number of bits of print data. The apparatus also includes an identification line coupled to a predetermined one of the latches and to the printer controller. The identification line provides to the printer controller one of the n number of bits from the identification data string that is latched into the predetermined one of the latches. Based upon whether the bit provided on the identification line has a first or second state, the printer controller determines whether the print head is of a particular type.
In yet another aspect, the invention provides a method for generating identification information related to at least one ink jet print head in an ink jet printer. The method includes the step of shifting a first identification data string into a first serial input shift register of a first print head, where the first identification data string has n number of bits. At least one of the bits in the first identification data string has a first state, and no more than nxe2x88x921 number of the bits in the first string have a second state different from the first state. The method also includes the steps of latching the n number of bits of the first identification data string from the n number of bit positions of the first shift register into n number of corresponding first latches, and accessing one of the bits of the first identification data string from a predetermined one of the first latches. Based upon whether the bit accessed from the predetermined one of the first latches has a first or second state, a determination is made whether the first print head is of a first type.